Wegovy Injection: What It Is, How It Works, and Whether It's Right for You

What the Wegovy injection actually does inside your body

Semaglutide, the active ingredient in the Wegovy injection, is a synthetic version of GLP-1, a hormone your gut produces naturally when you eat. When GLP-1 receptors in the brain and digestive system are activated, hunger signals quieten, fullness arrives sooner, and the stomach empties more slowly. The result for many people is that smaller portions feel satisfying and cravings for high-calorie foods reduce without deliberate effort. That shift in appetite is biological, not motivational.

The injection itself is subcutaneous, meaning it goes just under the skin rather than into muscle. Wegovy comes in a pre-filled, disposable pen; there is no assembly and no exposed needle to load. Each pen delivers one weekly dose. The licensed injection sites are the abdomen, the front of the thigh, and the outer upper arm. For practical guidance on choosing and alternating sites, the Wegovy injection site page covers the detail, but the core principle is straightforward: rotate around the site and avoid injecting into skin that is sore, bruised, or scarred.

The NHS medicines page for semaglutide explains the mechanism clearly and is worth reading alongside the patient information leaflet supplied with your pen.

The titration schedule and what the dose steps mean for you

One of the more common misunderstandings about the Wegovy injection is that starting on a low dose means the treatment is not yet working. It is not quite that simple. The escalation schedule, 0.25 mg rising through 0.5 mg, 1.0 mg, 1.7 mg and up to 2.4 mg maintenance, exists primarily to let your body adjust. Gastrointestinal side effects such as nausea, loose stools, and indigestion are most pronounced when the dose is new to your system; moving up gradually keeps them manageable for most people. The prescriber decides the timing of each step based on how well you are tolerating the current dose, not on a rigid calendar.

As of spring 2026, the MHRA also approved a higher 7.2 mg maintenance dose for adults with obesity (BMI 30 or above), initially delivered across three 2.4 mg pens per week and subsequently as a dedicated single-dose 7.2 mg pen approved on 14 April 2026. Whether that higher dose option is appropriate for you is a clinical question; your prescriber will review your history before any such step is considered.

The practical point worth knowing early: the pen is pre-set. You do not dial in a dose or adjust anything. If you want a more detailed walk-through of the injection technique itself, the step-by-step guide to using the Wegovy injection takes you through each stage.

Side effects and when to seek help

Gastrointestinal symptoms are the most commonly reported side effects of the Wegovy injection in the UK. Nausea tends to be the one people notice first; vomiting, constipation, diarrhoea, reflux, and burping also appear on the list. For most people these are mild to moderate and settle as the body adjusts, especially if food choices shift towards smaller, lower-fat meals during the early weeks. Staying well hydrated helps, particularly if loose stools occur.

A small number of people experience more significant reactions. Severe, persistent stomach pain that spreads towards the back, with or without vomiting, should be treated as urgent: it can be a sign of pancreatitis, which the MHRA flagged in a January 2026 Drug Safety Update on GLP-1 medicines. Get medical attention promptly if that pattern of pain develops. Signs of an allergic reaction, gallbladder problems, or significant mood changes also warrant contacting a clinician without delay. Any suspected side effect can be reported through the MHRA Yellow Card scheme, which exists partly to build the evidence base for newer medicines like this one.

Storage matters too. Wegovy pens should be kept refrigerated at 2–8°C; the patient information leaflet states the exact room-temperature window that applies once the pen is in use, and it is worth reading that section before you travel. If you are planning to inject away from home, the guidance on arm injections may be useful for occasions when your abdomen or thigh is less accessible.

Who the Wegovy injection is licensed for, and the private route

The UK licence covers adults with a BMI of 30 or above, or a BMI from 27 upwards where at least one weight-related condition is present, such as high blood pressure, type 2 diabetes, or high cholesterol. Lower BMI thresholds apply for some ethnic backgrounds under UK guidance. BMI alone does not determine suitability; the prescriber looks at your full health picture, current medicines, and medical history before reaching a decision.

On the NHS, Wegovy is recommended by NICE (TA875) only within a specialist weight management service, with multidisciplinary support, for a maximum of two years. Waiting times for those services are often long. Many people in the UK use a private, regulated online pharmacy as an alternative. If cost is part of your thinking, the Wegovy price comparison page sets out what UK private treatment typically involves. The broader picture of weight-loss treatment options is also worth reviewing if you are still deciding between injectable medicines.

At nume, every consultation is read by a GPhC-registered Independent Prescriber (a named clinician, not automated software) on the day you submit it. Treatment is dispatched the same day when clinically approved and arrives the next working day in plain packaging. To find out whether the Wegovy injections we offer are suitable for you, speak to our prescribers through a free consultation. You can also read more about the individual Wegovy injection strengths available if you want to understand which dose stage you might be starting from.